JPS6267564A - Image recording device and image forming method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary of the Invention] A voltage is applied between a photoconductor having island-like microelectrodes on its surface and a first developing machine to develop the image, and then an image is exposed from the back side to remove trapped charges. An image is formed and then a reverse bias is applied to the second developer to remove background toner.

[Industrial application field]

The present invention relates to an image recording device and an image forming method used in printers, etc., and in particular to an image forming method in which a toner image is formed in a bright area (n-front area) on a photoreceptor irradiated with image light based on an image pattern to be formed. The present invention relates to a recording device and an image forming method.

[Conventional technology]

Figure 2 shows charging, exposure, development, and
1 is a schematic diagram of a conventional so-called electrophotographic image forming apparatus that performs operations such as transfer. As shown in FIG. 2, a recording drum 1 is coated with a photoconductive layer 2 made of selenium or the like.
The upper surface is uniformly charged by an initial charging corona discharger 3. Next, the photoconductive layer 2 is exposed to light corresponding to image information using an exposure means 4 such as a laser to form an electrostatic latent image. Furthermore, toner of black fine particles charged to the same polarity as the uniform charge is electrostatically attached to this electrostatic latent image by an electric field by a developing device 5 to form a toner image. Thereafter, the toner image on the photoconductive layer 2-1 is transferred by a transfer corotron 6 onto a recording paper 10 charged with a charge of opposite polarity to that of the toner. The thus transferred toner image is fixed onto the recording paper IO by heat fixing, pressure fixing, or the like in the fixing device 7. On the other hand, the toner remaining on the photoconductive layer 2 is easily cleaned and removed by the fur brush cleaner 9 through a step of neutralizing the charges on the photoconductive layer 2 and the charges of the toner by a static eliminating corodor 8 or the like. The surface potential of the photoconductive layer 2 is made approximately zero. Image recording is completed through a series of processes from initial charging to cleaning of residual toner.

Thereafter, the above recording process is repeated.

As described above, the electrophotographic method requires a corona discharger to charge and remove static electricity from the photoreceptor. For this corona discharge, a high voltage of several kilovolts must be applied to the corona wire, which requires a high-voltage power supply, and corona dischargers are susceptible to humidity and dust, making them unreliable. Inferior.

In addition, the ozone generated by the corona discharger produces odor and has an effect on the human body. moreover,
6 steps: charging, exposure, development, transfer, neutralization, and cleaning
The disadvantage is that two processes are required, and the equipment for this process is complex and large.

Recently, as an alternative to the conventional electrophotographic process, an image forming method that does not use a corona discharger has been proposed in Japanese Patent Application Laid-Open No. 57-119375.
This has already been disclosed as an electrophotographic display in Japanese Patent Publication No. This device is shown in Figure 3A. IT on transparent substrate 11
A transparent conductive layer 12 made of O is provided, and a photoreceptor layer 13 made of a CdS binder binding layer with a thickness of 65 μm is provided thereon.
Furthermore, a white insulating layer 1 having a certain degree of resistance value is provided thereon.
A conductive magnetic toner developing device 16 is placed opposite to the recording film 15 having a structure in which the transparent conductive layer 12 is laminated with a semiconductor laser 17, a polygon scanner 18, and an fθ lens. Image exposure is performed via 19. Since a voltage is applied between the developing roller and the ITO, a light beam is irradiated as shown in FIG. 3B, and the photocharge runs toward the toner in the CdS portion of the photosensitive layer where the resistance has decreased, and as a result, the toner is The induced opposite charge attracts the toner onto the photoreceptor by Coulomb force. On the other hand, in the areas that are not irradiated with light, the thickness of the insulating layer is sufficiently large, so that the electrical adhesion is weak and the toner does not adhere to the photoreceptor. As a result, a toner image 20 corresponding to the exposure is formed on the photoreceptor. After image formation, the photocharge and toner-induced charges discharge through the surface layer within one cycle of image display. As a result, it is held on the developing roller again during the next image formation. On the other hand, image exposure was carried out without any problems.
New image formation becomes possible. In this method, since image formation is performed by utilizing the difference in Coulomb force acting on toner in exposed and unexposed areas, the film thickness of the photoreceptor must be made considerably thick. However, a photoreceptor with a thick film is difficult to manufacture uniformly, requires a large amount of photoreceptor material, and has the disadvantage that as the film thickness increases, the recording voltage increases and the photosensitivity decreases. . Further, when this image forming method is applied to a hard copy device, there are drawbacks such as difficulty in transferring to plain paper because the toner is a four-electrode toner.

An object of the present invention is to provide an image recording device and an image forming method that eliminate the above-mentioned drawbacks.

[Failure to solve the problem]

According to the present invention, the above-mentioned problem is solved by a photoreceptor having a transparent conductive film and a photoconductive layer sequentially disposed on a transparent substrate, and an image exposure means disposed facing the surface of the transparent substrate with the photoreceptor interposed therebetween. and a developing device disposed opposite to the surface of the photoconductive layer, and conveying charged toner between the developing device and the photoreceptor and applying a voltage between the developing device and the transparent conductive film. A plurality of island-like microelectrodes are arranged on the photoconductive layer, and the developing machine includes a first developing machine disposed opposite to the island-like microelectrode, and a predetermined developing machine from the first developing machine. The problem is solved by an image recording device characterized in that the second developing device is disposed opposite to the island-shaped microelectrode and is spaced apart from the second developing device.

Furthermore, according to the present invention, the above-mentioned problem is solved by applying a voltage between the first developing device and the transparent electrode using the above-mentioned apparatus to form a charged toner layer on the island-like microelectrode, and at the same time forming a charged toner layer on the transparent conductive film. Charge is induced, and then the photoreceptor is moved and light is irradiated from the base side in accordance with the image pattern to expose the photoreceptor, and the charge induced on the transparent conductive film is removed from the photoreceptor. What is the voltage applied to the first developing machine by trapping it on the surface of the exposed part of the photoconductive film of the body, then moving the photoreceptor, and applying it to the second developing machine which is arranged oppositely on the island-shaped electrode? By applying a voltage of opposite polarity to electrostatically remove charged toner adhering to non-exposed areas, and forming a toner image corresponding to a light irradiation pattern on the surface of the photoreceptor. is also resolved.

Hereinafter, the recording principle of the novel image forming method proposed earlier will be explained using FIGS. 4A, 4B, and 4C to briefly explain the present invention. A transparent conductive film 22 and a photoconductive layer 23 are provided on a transparent substrate 21 . A two-component developer consisting of insulating toner and carrier is conveyed onto the photoconductive layer 23, and a voltage is applied between the sleeve of the magnetic brush developing device 25 and the transparent conductive layer 22. In FIG. 4, a positive voltage Vbl is applied. Development is performed in this state to form a uniformly charged toner layer.

At this time, the photoconductive layer 23 functions as a capacitor, and a negative electric current of opposite polarity is induced in the transparent conductive film 22 in response to the charge of the toner layer 26 attached to the photoconductive film 23. Attached toner 1Mi in the r-th development step shown in FIG. 4A
is expressed by the following equation.

ρ.

Here, δ is the mass of the toner, p is the filling rate per unit volume of toner, and ρ8 is the volumetric charge density of the adhered toner layer in the image area, ε. is the permittivity of vacuum, ε is the relative permittivity of the toner layer,
d is the thickness of the photoconductive film.

The charge IQ of the toner layer at this time is expressed by the following equation: ρ.

However, q/m is the specific charge of the toner.

Next, after moving the photoreceptor, exposure is performed by irradiating laser light from the direction of arrow B in correspondence to the image pattern □ to be printed, as shown in FIG. 4B. Then, the charges 27 induced in the transparent conductive film 22 move to the surface of the photoconductive film 23 because the resistance of the photoconductive film 23 decreases due to the laser beam irradiation.

When the exposure is stopped at this point, the resistance of the photoconductive film 23 returns to the original, almost perfect resistance of the insulator. Therefore, the photoconductive film 23
The charge 27 that has moved to the surface becomes a trapped charge 28 and cannot move, and this becomes a latent image charge.

After further moving the photoreceptor, in the developing step (2) shown in FIG. 4C, the DC developing bias voltage Vt+Z is changed to the first
Contrary to the developing process, the voltage is applied so that the transparent conductive film 22 side is positive and the magnetic brush developing device 29 is negative.

Then, the positively charged toner in the non-image area where no latent image charge is formed is transferred to the second magnetic brush developing device 29 by the electric field of the second magnetic brush developing device 29 and the transparent conductive film 22. It will be collected inside. At the same time, the negatively charged free electrons 27 induced in the transparent conductive film 22 also gradually move toward the ground electrode, and eventually the free electrons induced in the transparent conductive film 22 completely disappear. do.

On the other hand, in the image forming section irradiated with light, some of the charged toner is transferred to the second magnetic brush developing device 29 and the transparent conductive film 22.
is recovered by the electric field between. At this time, the charges 28 trapped on the surface of the photoconductive film 23 cannot move because the photoconductive film 23 is an insulator.
By the same operation as the capacitor No. 3, the transparent conductive film 22 is
A positive charge of the same polarity 30'fJ< is induced on the top. Since the capacitance of the photoconductive film 23 is small when no light is irradiated, even for a slight positive charge 30 on the transparent conductive film 22,
The surface potential on the photoconductive film 23 increases (varies) and therefore becomes balanced with the developing bias voltage VbZ, and no more toner in the image area is collected electrostatically.

In this way, the charged toner 31 remains only in the image area,
A toner image is formed. Adhering toner at this time, l
Mo1 is a process in which the trapped charge Q obtained in the first development step is developed with the development bias voltage vbz,
It becomes as follows.

εd　　　　　　εd ρ, ε. ε.

However, Q is based on the second equation.

The fourth term in (3) indicates the latent image potential due to the trapped charges. Since the adhered toner fitMOi normally exhibits a positive value, by keeping this latent image potential higher than the development bias potential vbz in the (1)th development step, a sufficiently dark print can be obtained in the (2)th development step.

In the image forming method described above, trapped charges play an important role. Therefore, the present inventors clarified how trapped charges are distributed within a photoreceptor. The results are shown in FIG. FIG. 5 shows the light I+ after the first development.
<(Surface potential V on the toner layer in the exposed area by performing irradiation
This figure shows the relationship between t and the photoreceptor surface potential Vs immediately after the charged toner is blown away with N2 gas. Δ in Figure 5
The marks indicate the results of measuring the trap voltage Vs when using a photoreceptor in which a transparent R conductive film is provided on a transparent substrate and a photoconductive film is further provided thereon. Furthermore, the solid line is a theoretical value obtained on the assumption that trapped charges corresponding to the amount of charge of the attached toner are distributed at the interface of the photoreceptor.

Further, the broken line is a theoretical value obtained on the assumption that trapped charges corresponding to the amount of charge of the attached toner are uniformly distributed inside the photoreceptor. From this, the theoretical value indicated by the broken line and the experimental value are in good agreement, and it is considered that the trapped charges are uniformly distributed within the photoreceptor after the charged toner layer is removed.

This corresponds to the apparent doubling of the photoreceptor capacity, and in order to obtain a constant density, the recording voltage must be approximately doubled or more than in the case of trapped charges distributed on the photoreceptor surface. This means that it has to be higher.

In order to solve this drawback, the present inventors have devised a method of forming these trapped charges outside the photoreceptor, and moreover, on the surface of the photoreceptor. The mark ○ in Fig. 5 is based on the method of the present invention, using a recording medium with Cu7f3 adhered to the surface of the photoreceptor, and the trap voltage immediately after the adhered toner layer developed on this Cu7g is blown off with N2 gas. It shows. This revealed that when Cu7fA was provided on the surface of the photoreceptor, trapped charges were formed on the surface of the photoreceptor.

As described above, the amount of adhered toner obtained after the H-th development differs between the interfacial charge distribution where trapped charges exist on the surface of the photoreceptor and the bulk charge distribution where the trapped charges are uniformly distributed inside the photoreceptor as shown in the following equations.

Mik−δp(−(−d)+ε d 1Mib: Adhesive toner foot due to bulk charge distribution (4), 2(5)), the fourth term expresses the latent image potential (trap voltage) due to the trapped charges. It shows.

Comparing these two equations, it can be seen that if the trapped charge iQ is the same, the amount of adhered toner is greater in the second method (4) according to the present invention.

An embodiment in which the present invention is applied to a hard copy device will be described with reference to FIG.

The photoreceptor film 32 includes a transparent substrate 21, a transparent conductive film 22,
The film has a four-layer structure including a photoconductive layer 23 and an island-like microelectrode 33. The transparent base material 21 is a polyethylene terephthalate film with a thickness of 75 μm, the transparent conductive film 22 is an indium oxide vapor deposited film, and the photoconductive layer 23 is an organic semiconductor with a thickness of 10 μm.

An island-like microelectrode 33 was constructed by closely adhering a mesoche pattern of several μm square onto the film constructed in this way, and depositing nickel thereon. The island-like microelectrode 33 has a diameter of 7 I, per 100 μm, and 2.
Approximately 3 pieces are preferable.

Two magnetic brush developing machines 34 are in contact with the island-like microelectrode surface.
, 35 are provided. The magnetic brush developing machine 34 and the magnetic brush developing machine 35 are integrated and housed in one housing 36. An LED 37 and a SELFOC lens 38 are provided between the magnetic brush developing device 34 and the magnetic brush developing device 35 and on the transparent substrate side as an exposure light source.
was installed. Furthermore, a conductive rubber roller 41 is provided as a means for transferring the toner image 39 onto the recording paper 40. Also,
A fur brush cleaner 43 is provided to remove toner 42 remaining on the photoreceptor film, and a discharge lamp 44 is further provided to remove trapped charges and surface charges.

The magnetic brush developing machines 34 and 35 both rotate sleeves, and the peripheral speed of the sleeves is 30 cm/s.
'Non-magnetic with a particle size of about 0μm! ! Extramarginal toner 10-1
It is a two-component developer in which a carrier, which is iron powder of about 5 μm, is mixed at a weight ratio of 20%. The specific charge of the toner is 10μc/
It was g.

The operation of this embodiment will be explained below.

The photoreceptor film is moved endlessly in the direction of the arrow at a circumferential speed of 10 c.
Run at m/s.

Development is performed by applying a developing bias voltage Vb+ of 300 V between the transparent conductive film 22 and the '411 brush developing device 34 to form a uniformly charged toner layer. At this time, negative charges of opposite polarity corresponding to the amount of attached toner are induced on the transparent conductive film. Thereafter, the LED 37 is controlled according to the image information, and negative exposure is performed through the SELFOC lens 38. In the exposed area, photocarriers are generated within the photoconductive layer 23, and electrons reach the island-shaped microelectrode 33 via the photoconductive layer.
The potentials of the transparent conductive layer and the island-like microelectrode become almost the same.

At this time, the same amount of negative charge of the opposite polarity as the charge on the charged toner layer developed by the magnetic brush development 634 moves to the surface of the island-like microelectrode via the transparent conductive layer 22 and the photoconductive layer 23. . Then, when the exposure is finished, the photoconductive layer becomes highly resistive and can no longer be moved.

Next, a developing bias voltage V, 2=-100V, which is opposite to that of the magnetic brush developing device 34, is applied to the magnetic brush developing device 35,
develop. Then, in the image area, some of the charged toner is collected by the action of the electric field.

However, at this time, since the electrons trapped on the island-like microelectrodes cannot move, positive charges of the same polarity as the charged toner are induced on the transparent conductive layer 2 according to the amount of charge of the collected charged toner. Ru. Since the capacity of the photoconductive layer in the dark area is small, the surface potential of the photoconductive layer changes greatly even with a slight positive charge, and is balanced with the developing bias voltage Vb2. Then, no more toner in the image area is collected. On the other hand, the positively charged toner in the non-image area gradually begins to be collected into the developing device 35 by the electric field.

At the same time, the electrons induced on the transparent conductive film 22 also gradually move to the ground side, and eventually the free electrons induced on the charged toner layer and the transparent conductive layer completely disappear. As a result, the toner adhering to the non-image area is completely collected into the developing device 35.

The toner image 39 thus formed is electrostatically transferred onto the recording paper 40 by a conductive rubber roller 41 to which a voltage of opposite polarity to that of the charged toner is applied. Residual toner on the photoreceptor layer that has not been transferred is removed by a fur brush cleaner.

Then, the trapped charge and the surface charge on the photoreceptor surface are
The static electricity is eliminated by the static elimination lamp 44. Printing is performed continuously by repeating the above process.

In this way, in this embodiment, the print density is 0. D.

=1.0 or more, fog density 0.0. A dark print with no fog of 0.02 or less was obtained. On the other hand, in the novel image forming method proposed earlier (Japanese Patent Application No. 173636/1983), 0.0. In order to obtain V = 1.0 or more, a developing bias voltage Vb+ of 700 V or more was required. but,
According to the method of the present invention, there is an advantage that the recording voltage can be reduced to about 172V. Furthermore, since island-shaped microelectrodes are used, there is a secondary effect that the edge effect effectively acts even on solid black images.

Furthermore, even when compared with the case where the conventional image forming method shown in FIG. 3A is applied to a hard copy device, in this example, (1) the photoconductive layer thickness is approximately 10 μm (approximately 175 μm or less in the conventional method); This reduces the manufacturing cost of the photoreceptor film.

■Thinner photoreceptors have higher photosensitivity.

■ Insulating toner can be used and transfer to plain paper is easy.

It has various features such as.

[Effects of the Invention] As explained above, according to the present invention, there is no need to use a corona discharger, so high voltage is not required, and
It is less susceptible to the effects of humidity, dust, etc., improving reliability.

Further, it has the advantage that it is a simple process and can record at a lower voltage than the novel image forming method proposed earlier (Japanese Patent Application No. 173,636/1982). Furthermore, since the present invention allows the use of insulating toner, there is an advantage that when the present invention is applied to a hard copy device, transfer to plain paper becomes possible.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining an embodiment in which the present invention is applied to a hard copy apparatus, and FIG. 2 is a schematic diagram for explaining a conventional electrophotographic image forming apparatus. 3A and 3B are schematic diagrams for explaining an electrophotographic display device which is an example of another conventional recording method, and FIG. FIG. 5 is a diagram for explaining the printing principle of the forming method;
The figure is a diagram for explaining the present invention in detail. ■... Recording drum, 2... Photoconductive layer, 3...
- Corona discharger, 4... Exposure means, 5... Developing machine, 6... Transfer corotron, 7... Fixing device, 8... Static elimination corotron, 9.43...
Fur brush cleaner, 10, 40...recording paper,
11, 21... Transparent substrate, 12... Transparent conductive layer, 13... Photoreceptor layer, 14... White insulating layer,
15...Recording film 516...Developing machine,
17... Semi-conductive laser, 18... Polygon scanner, 19... FD lens, 20, 39... Toner image, 22... Transparent conductive film, 23... Photoconductive layer, 2
6... Toner layer, 27... Charge, 28...
Trap charge, 30... Positive charge, 31... Charged toner, 32... Photoreceptor film, 33... Island-like microelectrode, 34, 35... Magnetic brush developing device, 36... Housing , 37... LED (light emitting diode), 38... SELFOC lens, 41... Conductive rubber roller, 44... Static elimination lamp.

Claims (1)

[Scope of Claims] 1. A photoreceptor in which a transparent conductive film and a photoconductive layer are sequentially disposed on a transparent substrate, an image exposure means disposed facing the surface of the transparent substrate with the photoreceptor interposed therebetween; An image recording apparatus comprising a developing device disposed opposite to the surface of the photoconductive layer, transporting charged toner between the developing device and the photoreceptor, and applying a voltage between the developing device and the transparent conductive film, as described above. A plurality of island-like microelectrodes are disposed on the photoconductive layer, and the developing machine includes a first developing machine disposed opposite to the island-like microelectrode, and a predetermined distance from the first developing machine. An image recording apparatus characterized in that the second developing device is arranged opposite to the island-like microelectrode. 2. A photoreceptor in which a transparent conductive film and a photoconductive layer are sequentially disposed on a transparent substrate, an image exposure means arranged opposite to the surface of the transparent substrate, and an image exposure means arranged opposite to the surface of the photoconductive layer via the photoreceptor. An image recording apparatus comprising a developing machine installed on the photoconductive layer, conveying charged toner between the developing machine and the photoreceptor, and applying a voltage between the developing machine and the transparent conductive film. a plurality of island-like microelectrodes are disposed, the developing machine is arranged to face the island-like microelectrodes, a first developing machine is provided, and the island-like microelectrode is arranged at a predetermined distance from the first developing machine; In an image forming method using an image recording device characterized in that the second developing device is disposed opposite to the electrode, a charged toner layer is formed by applying a voltage between the first developing device and the transparent electrode. forming on the island-shaped microelectrode and inducing charges in the transparent conductive film, then moving the photoreceptor and irradiating light from the base side in accordance with the image pattern to expose the photoreceptor; The charges induced on the transparent conductive film are trapped on the surface of the exposed portion of the photoconductive film of the photoreceptor, and then the photoreceptor is moved to perform a second development process disposed oppositely on the island-shaped electrode. A voltage with a polarity opposite to that applied to the first developing device is applied to the developing device to electrostatically remove the charged toner adhering to the non-exposed area, and also to apply a voltage on the photoreceptor surface corresponding to the light irradiation pattern. An image forming method characterized by forming a toner image.